如何将UILabel放在UITextField的最后一个字符旁边？

Question

I am trying to achieve the same effect as Facebook's new status field: place something next to the last character which cannot be modified or selected by the user (for example, a tag: "with Joh Doe").

What's the best way of achieving it?

Thanks

Nick

Answer 1

An easier solution would be to simply make the last n characters in the TextView not editable. Then let the TextView handle moving and wrapping the text as needed. I would guess that is what Facebook is doing, just with some attributed text at the end.

In your ViewControllers.h, make sure the viewController conforms to the UITextViewDelegate as follows.

@interface ViewController : UIViewController <UITextViewDelegate>

Then in the viewDidLoad: method, set the delegate for the UITextView to the ViewController. You can also add your fixed text.

- (void)viewDidLoad
{
    [super viewDidLoad];
    // Do any additional setup after loading the view, typically from a nib.

    self.myTextView.delegate = self;
    self.myTextView.text = " posted by Mike";
}

Then, we will use the shouldChangeCharactersInRange: method to prevent the user from editing the text at the end you want to preserve.

- (BOOL)textView:(UITextView *)textView shouldChangeTextInRange:(NSRange)range replacementText:(NSString *)text
{
    BOOL deleteKeyPressed = ([text length] == 0 && range.length > 0);

    if( range.location > (textView.text.length - @" - posted by Mike".length) || (deleteKeyPressed && range.location > (textView.text.length - @" - posted by Mike".length)) )
    {
        return NO;
    }
    return YES;
}

I think this should get you started and make you life easier than finding the end of the last text, then putting another view at the end that may need to wrap if there is not enough room to fit it.

So to prevent the user from selecting the "reserved" text, add the following delegate method to your ViewController's .m:

-(void) textViewDidChangeSelection:(UITextView *)textView
{
    if( textView.selectedRange.location > (textView.text.length - @" - posted by Mike".length) )
    {
        [textView setSelectedRange:NSMakeRange((textView.text.length - @" - posted by Mike".length), 0 )];
    }
}

You'll still need to handle if the user selects all the text, and chooses to "cut" or "paste", but that should just be another special case in shouldChangeTextInRange . I'll let you figure that one out - shouldn't be hard. Certainly a lot easier than trying to dynamically place, size, and wrap a TextView within another TextView.